Electrical apparatus



Dtc. 9, 1947. A DQRNE 2,432,230

ELECTRICAL APPARATUS Filed March 29, 1946 l: IG. 2

`mwiwron ARTHUR ooRNE v y BY l "7W ifi/,Luna

AT TVQRNEY lPatented Dec. 9,1947

UNITED STATES PATENT OFFICE.,

ELECTRICAL APPARATUS States of America,

tary of War Arthur Dome, Freeport. N. Y., assigner to United asrepresented by the Secre- Appiication March 29, 1946, Serial No. 657,940

2 Claims.

ventional switches, operable at low radio frequencies, areunsatisfactory for use at high frequencies because of their geometricalconfiguration and electrical properties. Even the simple conventionalsingle pole double throw switch,

representative of low frequency switching devices, presents an impedancemismatch tolines carryinghigh Ifrequency currents and has suiiicientcapacitive coupling between elements to prohibit its"\i1se with highfrequency circuits. This impedance mismatch and capacitive cou- .plingcauses standing waves and undesirable cross talk in high frequencycircuits.

The availability of aswitching device, operable at high radiofrequencies, wouldr find wide' usage in electrical apparatus.

- It is an object of the present invention to provide-a switching deviceparticularlyadapted for use in electrical circuits carrying highfrequency currents.

It is another object to provide a single pole` double throw switch foruse with electrical ciry cuits carrying high frequencyV currents.

It is also an object to provide an electrical switching device which hasa low value of capacitance between switching elements and which has avalue of characteristic impedance of the order of the characteristicimpedance of common coaxial transmission lines.

An electrical switching device, which accomplishes the aforesaid'objectconsists of a rectangular block of metal with a single conventionalcoaxial transmission line connector attached to one end and with twosimilar connectors attached to the other end of the metallic y block. fv

Each of the three cable connectors are interconnected by tubularpassages cut in the metallic block. These interconnecting passagesintersect to form a Y, with the leg of the Y leading to the singleconnector at one end of the metallic block and with the arms of the Yleading to the pair of connectors at the other end of the metallic blockThe periphery of each of these passages forms the outer conductor of oneof three intersecting coaxial transmission lines and each passageconcentrically encloses a center conductor. Thus, three intersectingcoaxial transmission lines are formed. Where the center conductors wouldnormally intersect, a nonmetallic plunger is inserted in the metallicblock and is fastened to each of the center conductors of the coaxialtransmission lines forming the legs of the Y.

These two center conductors, which are fastened to the plunger, arearranged so that when one is in contact with the center conductor of thecoaxial transmission line forming the leg of the Y, the other centerconductor is grounded to its outer conductor. Longitudinal movement ofthe plunger reverses the condition of the twoA center conductors of thecoaxial transmission lines forming the legs of the Y.

Other objects, features and advantages of this invention will suggestthemselves to those skilled in the art and will become apparent from thefollowing description of the invention taken in connection with theaccompanying drawing in which:

Fig. 1 is a plan view of a device embodying the principles of thisinvention; and.

of the block and two similar coaxial transmis- Fig. 2 is an elevation ofFig. 1 with a portion cut away to show the internal mechanism.

Referring now to Fig. 1. a rectangular metallic block consisting of twosimilar halves, upper half I 0 and lower halt II, is held together bybolts such as I2. A conventional coaxial transmission line connector I3is attached to one end sion line connectors .I4 and I5 respectively, areattached to the other end of the block.

Grooves having a semi-circular cross section are milled in each half I 0and II of the metallic block. The grooves cut in half I0 coincide withthe grooves cut in half I l, resulting in a passage whose total crosssection is in the form of a circle. These passages interconnect thethree connectors' I 3..I4 and I5, and intersect to form a Y with the legof the Y leading to connector I3 and with th'e arms of the Y leading toconnectors I4 and I5.

The periphery of each of these passages forms the outer conductor of acoaxial transmission line. A center conductor I 5 is coaxially containedin the passage leading to connector I3 and similarly, center conductorsI6 and II are contained in the passages leading to` connectors Il andI5. These center conductors are held in place by spacers I8, I9 and 20.At the intersection of the passages, two spring'leaves 2| and 22 areattached to operating plunger 2:3. An end of leaf 2I is connected tocenter conductor I6 and an end of leaf 22 is connected to centerconductor 3 I1. The other ends of leaves 22 and 22 are silver plated toreduce contact resistance.

Referring now to Fig. 2, it can be seen that longitudinal movement ofplunger 2l forces the silver plated end of leaf 2i against the upperhalf I0 of the metallic block and that the silver plated end of leaf 22is forced against conductor IU.

Longitudinal movement of plunger 2l in the opposite direction forces thesilver plated end of leaf 2| in contact with conductor l5 and forces thesilver plated end of leaf 22 in contact with the lower half il of themetallic block. The end of conductor It, which makes contact 4withleaves 2l and 22, is flattened and is also silver plated to reducecontact resistance. The principle of this device is similar to that of asingle pole double throw switch. When plunger 23 is in one position,there is electrical continuity between connector I3 and connector I4,and at the same time, the inner conductor leading from connector I! isgrounded. Consequently,` there can be no cross talk between the circuitsassociated with connector l5 and the circuits associated with the othertwo connectors.. When plunger 2l is in the other position, thre iselectrical continuity between connector l and connector lli. and at thesame time the in'ner conductor leading from connector I4, is grounded.Thus the eiect of any capacity existing between parts of the switchingdevice is nulliiled.

Impedancel mismatches due to this switching device are minimized by theproper design of its components. The relative size of the inner andouter conductors of this switching device is proportioned to obtain acharacteristic impedance which is comparable in value to thecharacteristic impedance of commonly used coaxial transmission lines.

A switching device constructed'according to the teachings of thisspecification has been found operable at frequencies as high as 5000megacycles.

It will be apparent that there may be deviations from the invention asdescribed which still fall fairly within the spirit and scope of theinvention.

Accordingly all such deviations are claimed which fall fairly within thespirit and scope of the invention as identified in the hereinafterappended claims.

What is claimed is:

1. A switching device for use with high frequency electrical currentsincluding a rectangular metallic block with three intersecting holesdrilled in said block to form the periphery of the outer conductors ofthree coaxial transmission lines, two flexible center conductors eachconcentrlcally enclosed by one oi' said outer conductors of saidtransmission lines, one rigid center conductor concentrically enclosedby one of said outer conductorsl of said transmission lines and anonconducting operating plunger inserted in said metallic block near theintersection of said transmission lines with said flexible centerconductors attached to said plunger whereby movement of said plungerforces one of said flexible center conductors into electrical contactwith said rigid center conductor and simultaneously the other ci saidtwo flexible center conductors is forced into electrical contact withits outer conductor.

2. A switching device for use with high frequency electrical cimentsincluding three intersecting coaxial transmission lines each comprisingan outer conductor and a center conductor with two of said centerconductors made of ilexibie material and with the other center conductormade of a rigid material, a control plunger inserted in said coaxialtransmission lines at their intersection and attached to said twoilexible center conductors whereby movement oi' said plunger forces oneof said two flexible center conductors into electrical and physicalcontact with its outer conductor and simultaneously the other of saidtwo flexible center conductors is forced into electrical and mechanicalcontact with said rigid center conductor.

ARTHUR DORNI;

REFERENCES 0mm UNITED STATES PATENTS Name Date Schriener T- Nov. 25,1941 Number

